Bead Profile
Raised ridges formed on both sides of a scored groove represent the primary zones of localized compression in paperboard creasing. The crease shoulder is the elevated, rounded structure created when the male creasing rule forces the substrate into the female channel, displacing fibres outwards. This displacement establishes the hinge axis for subsequent folding operations.
Its symmetry and height determine how cleanly the fold follows the intended score line without drifting.
Material Stress
High localized shear stress occurs in the fibrous matrix immediately adjacent to these elevated beads. During creasing, the paperboard is subjected to tension on the outer ply and compression on the inner plies, forming the crease shoulder through plastic deformation. If the board is too dry or has low long-fibre content, these shoulders will crack or tear, which weakens the joint and leads to dust generation on high-speed gluer lines.
Proper board conditioning remains necessary for ensuring that the fibre plies can slide over each other without fracturing.
Mechanical Measurement
Digital profiling systems measure the elevation and contour of these raised regions to ensure consistency. A profile with uniform height across both sides of the groove prevents the fold from skewing or forming an uneven edge. Operators adjust the width of the female creasing matrix to control the volume of displaced material, ensuring the crease shoulder achieves the required geometry.
This calibration supports consistent erecting behavior during carton filling.
